OptionTree Date Picker Option Type

gistfile1.php

array(
    'id'          => 'spyr_demo_date_picker',
    'label'       => __( 'Date Picker', 'text-domain' ),
    'desc'        => __( 'Your description', 'text-domain' ),
    'type'        => 'date-picker',
    'section'     => 'your_section',
)

// Get the value saved on Theme Options Page
$spyr_demo_date_picker = ot_get_option( 'spyr_demo_date_picker' );

// Get the value saved for a Page, Post or CPT ( Within the loop )
$spyr_demo_date_picker = get_post_meta( $post->ID, 'spyr_demo_date_picker', true );

// Checking if the date has passed
$date = new DateTime( ot_get_option( 'spyr_demo_date_picker' ) );
$now  = new DateTime( "now" );

// Compare the 2 dates
// Not that this example assumes you have not changed the date format
// through the ot_type_date_picker_date_format filter like shown below
if( $now > $date ) {
    echo 'Date is in the past';
} else {
    echo 'Date has not passed yet';
}

// Change displayed format and returnd value
// Defaults to yy-mm-dd
// Not recommended but it's possible
add_filter( 'ot_type_date_picker_date_format', 'spyr_modify_date_picker_date_format', 10, 2 );
function spyr_modify_date_picker_date_format( $format, $field_id ) {
    if( 'spyr_demo_date_picker' == $field_id ) {
        return 'mm-dd-yy';
    }
}